What Happens if You Don’t Change a Furnace Air Filter

By | April 11, 2024

What Happens if You Don't Change Air Filter in a Furnace
As an HVAC tech, I get many calls on furnaces that do not work with a wide variety of problems.

One of the top problems, and a preventable one, is a dirty air filter which can cause many furnace issues.

A common issue is a dirty filter block the airflow into the furnace, which causes it to become too hot and shut down.

When a furnace does not have good airflow, the heat exchanger will become overheated, and the high limit switch will shut the furnace off.

This stops the heat exchanger from becoming cracks and letting noxious gases into a home.

I have had many calls to homes with a furnace that turns on but shuts off a short while later (Short Cycling), only to find it has a dirty air filter.

Even worse, some homeowners will remove the filter completely and not replace it with a new one, which clogs up internal components such as the A-coil.

What happens if you Forget to Change the Air Filter in a Furnace?

  • Internal Components Such as A-Coil become Clogged
  • High Limit Switch Shuts Off Furnace (Short Cycles)
  • Blower Motor Life is Shortened

How Long Can You Go Without Changing the Air Filter?

Most furnace air filters are replaced every 60-90 days, but in some regions, they are changed more often.

For example, in the desert Southwest, with more sand particles in the air, the filters are often changed monthly.

Pollution inside a house can also be a factor, such as a home with a smoker will need to replace the filter more often.

The main thing with any filter is that air can pass through easily without mall debris blocking it.

How Do You Change an Air Filter on a Furnace?

Almost all furnace air filters are located at the bottom of the furnace.

It will have dimensions that must be used to get a good fit and not let any unfiltered air pass.

For example, a 20×24 filter will be the dimensions, and any new 20×24 filter can be used to replace it.

There are different types of filters that can be bought with a higher filtration, but any lower-cost filter will work to keep debris out.

High filtration filters are good fr those who want better indoor air quality.

A furnace can work well for many years is basic maintenance if done periodically, including changing the filter when required.

Replacing the filter is easy to do and will greatly improve how the furnace works and the indoor air quality.

Most filters are replaced every 60-90 days, but some regions may need the filter replaced more often.

Be sure to keep an extra filter on hand as they are low-cost items that will help keep a furnace working for many years.

Category: Furnace repair Heating

About Aaron H. Benetti

Aaron H. Benetti an HVAC technician who has worked in the field since 1991. He began his career as an HVAC installer and later began doing troubleshooting and repairs. Around 2010, he began to write books on HVAC topics, mainly tutorials and how-to information. Currently, Aaron works as an HVAC tech and also writes many articles and posts for websites as well as books and videos on HVAC topics.

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